1. Field of the invention
The present invention relates to a breast roll shake for use in a paper-making machine, and, more particularly, to a vibration compensated breast roll shake for use in a paper-making machine.
2. Description of the related art
A paper-making machine typically includes a headbox having an outlet from which is discharged a fiber suspension having a substantially constant cross-section across the width of the paper-making machine. The fiber suspension is guided onto an endless fabric or "wire" belt which is carried by a so-called breast roll. In such a machine, it is known to move the breast roll in reciprocating fashion in a direction parallel to the longitudinal axis of the breast roll. Such movement of the breast roll imparts a fluid shear in the fiber suspension carried on the wire belt and prevents flocculation of the fiber suspension while a paper web is being formed by dewatering of the fiber suspension. One known method of moving the breast roll is to use a so-called breast roll shake having a rotatable crank shaft attached to a connecting rod. The connecting rod interconnects one end of the breast roll with the crank shaft. Rotation of the crank shaft causes the arm to move the breast roll in reciprocating fashion in a longitudinal direction thereof. The breast roll is attached to a fiberglass mounting which allows the reciprocating movement thereof.
A problem with conventional breast roll shakes is that at least a portion of the forces transmitted to the breast roll by the breast roll shake are also transmitted to the mountings which hold the breast roll shake unit to a fixed surface. Since a breast roll can weigh about 21,000 pounds or even larger, the force which is exerted on the mountings of the breast roll shake unit can likewise be large, resulting in fatigue failure thereof.
Another problem with known breast roll shakes is that the cam shaft operates at a particular rotational speed, resulting in a breast roll having a velocity profile curve which is substantially sinusoidal. With known breast roll shakes, it is not possible to change the velocity profile curve of the breast roll reciprocating movements (other than amplitude and frequency).
What is needed in the art is a breast roll shake which offsets the momentum of the moving breast roll, thereby substantially eliminating fatigue stress on the mounting between the breast roll shake and fixed surface.
What is further needed in the art is a breast roll shake which moves the breast roll such that different velocity profile curves thereof may be realized.